Lehmann lovegrass Eragostis lehmanniana is a drought tolerant bunchgrass native to southern Africa.It was introduced to Arizona (southwest USA) over 50 years ago for erosion control and forage production. Depending on management objectives, it may now be viewed as an undesirable invasive or an important ground cover and forage plant. To inform management (whether to reduce or enhance presence) effect of burn season compared to no burning on germinability of Lehmann lovegrass in the seedbank was investigated on the Santa Rita Experimental Range, southern Arizona.
In January 1984, a 3 ha area of almost 100% lovegrass cover was fenced and divided into 48, 15 x 15 m plots (separated by 2 m wide fire breaks). Treatments (replicated 3 times; applied to different plots in 1985) assigned in a randomized block design were: winter (February), early summer (June), mid-summer (July), and autumn (November) burned (by head fires), plus unburned (control) plots.
Within each plot, five soil samples (approximately 8 x 15 x 2 cm deep) were collected immediately after burning for bioassay, likewise in unburned plots. Soil samples were placed in Styrofoam cups (perforated bottom) over moist sterile sand. Lehmann lovegrass seedlings were counted daily as they emerged for 42 days.
To assess seedling emergence in the field, seedling density was sampled on 1984 unburned and burned plots. Seedlings were counted in 50 (5 x 30 cm) quadrats in each plot in August and December 1984, and May 1985.
Lehmann lovegrass seedling emergence from burned plot bioassay samples (average 342 seedlings/m²) was nearly 40% more than from unburned plots. This increase in fire-associated germinability may be important in its observed ability to re-establish where mature plants are killed by burning.
Significantly more seedlings emerged from samples collected in June (i.e. before the summer rainy season; average 700/m²), being over twice that from any other collection period (February, July and November).
Compared to unburned plots (average 20 seedlings/m²) seedling densities in the field were much higher in burned plots regardless of burn season (February burn 120/m²; June burn 113/m²; July burn 80/m²).
If using or referring to this published study, please read and quote the original paper, this can be viewed at: https://www.uair.arizona.edu/holdings/journal/issue?r=http://jrm.library.arizona.edu/Volume41/Number5/